Network edge detection and notification of gas pressure situation

ABSTRACT

Techniques for detecting and remediating a low gas pressure situation within a gas delivery system are described. In one example, a smart gas metering device measures gas pressure. The first device determines that the gas pressure value is less than a first threshold value, indicating a low gas pressure condition. The first smart metering device reports this condition to a second smart metering device, which may be nearby. In response, the first smart metering device receives gas pressure information from the second smart gas metering device. The first smart gas metering device then reports one of two conditions to a headend device, such as a main office server. In a first possibility, the report indicates a low gas pressure event confined to the first device. Alternatively, the report indicates a low gas pressure event within a distribution area comprising the first device and the second device.

RELATED APPLICATIONS

This patent application claims benefit of priority to U.S. patent application Ser. No. 17/127,896, titled “Network Edge Detection and Notification of Gas Pressure Situation”, filed on Dec. 18, 2020, which is incorporated herein by reference.

BACKGROUND

If gas pressure within a portion of a gas distribution system gets too high, it can cause pipes to burst, the venting of gas, dangerous pilot lights, damage to appliances and/or buildings, and even fires and explosions. Monitoring gas pressure is a complex matter, in part because pressure can vary due to many factors, including gas supply, user gas demand, pipe lengths, bends, joints, and gas friction with pipe interiors and other gas. Moreover, known systems tend to respond slowly to over-pressure events, in part because of latencies within communication networks, headend application latencies, and human delays. Accordingly, substantial gas pressure increases can result in damage before the increases are detected, reversed and/or mitigated.

Low gas pressure events are also concerning for utility companies and their customers. Loss of gas pressure due to high demand during winter can result in service failures at the sites of residential and commercial customers, and lead to pilot lights extinguishing. Utilities routinely offer pilot light relighting services to their end customers. While this is frequently free to the end customer, it is very costly to utilities if needed at a large number of service points.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components. Moreover, the figures are intended to illustrate general concepts, and not to indicate required and/or necessary elements.

FIG. 1 is a diagram showing an example gas delivery system illustrating devices used in detection and notification of gas pressure abnormalities.

FIG. 2 is a diagram showing an example gas delivery system illustrating the function of groups of devices, such as in data-gathering.

FIG. 3 is a diagram showing an example gas delivery system illustrating the function of groups of devices, such as in data-utilization.

FIG. 4 is a diagram showing an example gas delivery system illustrating data collection, data transmission, and data utilization.

FIG. 5 is a flow diagram showing an example of detecting a high gas pressure condition.

FIG. 6 is a flow diagram showing example techniques for selecting a second device to which to send a message.

FIG. 7 is a flow diagram showing example techniques for responding to a high gas pressure condition.

FIG. 8 is a flow diagram showing additional example techniques for responding to a high gas pressure condition.

FIG. 9 is a flow diagram showing example techniques for defining and using groups of devices to detect a gas over-pressure condition.

FIG. 10 is a flow diagram showing example techniques for detecting and responding to a low gas pressure condition.

FIG. 11 is a flow diagram showing example techniques for determining if a response to a low gas pressure condition should include increasing a data-sampling rate of a pressure sensor or closing a service valve.

FIG. 12 is a flow diagram showing example techniques for maintaining data on gas service sites and using priority data to determine service sites to shut down (e.g., closing a gas service valve) during a low gas pressure condition.

FIG. 13 is a flow diagram showing example techniques for maintaining data on gas service sites and using priority data to set threshold values used to manage a low gas pressure condition.

FIG. 14 is a flow diagram showing example techniques for using a rate of change of gas pressure to determine if a service valve at a service site should be closed.

FIG. 15 is a flow diagram showing example messaging sent to gas service customers and to a headend device.

FIG. 16 is a flow diagram showing example use of grouped devices and related techniques to alleviate a low gas pressure condition.

FIG. 17 is a flow diagram showing example techniques for determining that a group of devices at a respective group of service sites should close their respective service valves in response to a low gas pressure condition.

FIG. 18 is a flow diagram showing example techniques for maintaining a data structure, and using the data structure in a process by which gas supply and demand are regulated during a low gas pressure condition.

FIG. 19 is a flow diagram showing example techniques for using groups of devices to detect and report low gas pressure conditions.

FIG. 20 is a flow diagram showing example techniques for accessing and/or updating a database, such as to obtain or provide gas pressure data and/or a topological relationship of devices on the network.

FIG. 21 is a flow diagram showing example techniques for accessing a database, obtaining information, and using the information to determine if a service valve should be closed.

FIG. 22 is a flow diagram showing example techniques for grouping devices and managing the grouped devices.

DETAILED DESCRIPTION Overview

Techniques for detecting a high gas pressure situation within a gas delivery system (e.g., for delivery of natural gas to homes and businesses) are described. In one example, a first device measures gas pressure. If a gas pressure that is over a threshold value is detected, the first device sends a message to a second device, which may be near the first device (e.g., both devices may be on a same gas delivery pipeline). The second device may respond by indicating its own gas over-pressure condition, thereby suggesting that the gas over-pressure condition is not localized at the first device (e.g., a first smart gas meter). Alternatively, the second device may not detect and/or report an over-pressure condition, thereby suggesting that the over-pressure condition may be localized to the first device.

In a further example, the first device may share information about its over-pressure condition with devices within a group defined to include the first and the second devices and other devices. Members of the group may share information with devices in any group(s) in which they are members and/or with devices that are within a threshold physical (geographic) distance. An appropriate response may be made within the gas delivery system depending on if the over-pressure condition is localized to the first device, or more widely present within the group of devices. In examples, protective measures may be taken, such as closing valves providing gas to appropriate service sites, and such as sending warning notices to a headend device (e.g., to the utility company), to users' devices including users' cellphones and in-home devices, and to any other device(s) that may assist in mitigating damage and/or injury.

Example System and Techniques

FIG. 1 shows an example gas delivery system 100. If pressure in an area of the gas distribution system 100 is too high, the pressure may cause damage. The gas delivery system 100 is configured having devices and techniques of operation that detect, notify, and mitigate or resolve overly high gas pressure conditions.

In the example system 100, a major gas main 102 supplies gas to several local gas mains 104, 106. In the example, the local gas main 104 supplies gas to large gas volume customer(s) 108 having associated gas pressure regulators and metering devices 110. The local gas main 106 supplies gas to commercial customer(s) 112 having associated gas pressure regulators and metering devices 114. The local gas main 106 also supplies gas to residential customer(s) 116, 118 having associated gas pressure regulators and metering devices 120, 122.

The local gas main 104 and the devices attached to it may constitute a group of devices for purposes of an algorithm (discussed at FIGS. 5-9 and other locations) that detects, notifies and/or mitigates/resolves a situation wherein devices within the logical group detect gas pressure over a threshold value. The group may be based at least in part on knowledge of the topology of the gas delivery system. A topological description of the gas delivery system may be configured within a database or other data structure. In an example, the topological description may include a listing of devices in the system, their characteristics, and how, when, where, and/or to what they are connected. The topology may include “states” of devices, such as a valve being open or closed, or a gas main having a certain pressure, a battery having a certain charge, etc. Similarly, the local gas main 106 and devices attached to it may constitute a second group. Each device in the system 100 may be considered to be in one or more groups. The groups may be formed in a manner that logically groups devices so that data from one device may be synergistically interpreted using data from other device(s) in the group. For example, if one device recognizes a gas pressure over a threshold pressure value, that event is reported to other devices in a group. A confirmation of high pressure by other devices in the group tends to indicate a region of high gas pressure rather than an area of localized high gas pressure.

A liquid natural gas (LNG) plant 124 provides gas to the delivery system 100 at local gas main 126. Compressor stations 128 create, regulate and/or maintain the gas pressure within gas mains and local delivery pipes within the system 100. An underground gas storage reservoir 130 and regulator 132 provide additional gas through a gas pipe 134 to the system 100.

Within the system 100, gas flows from locations having higher gas pressures upstream (e.g., the LNG plant 124, the compressor stations 128, and the underground storage 130) and to areas having lower pressures downstream (e.g., the customers 108, 112, 116 and 118).

Additionally, the gas pressure within the gas delivery system 100 can vary from city gate regulators/meters 136 in the system to the downstream service point gas pressure regulators and meters. Example factors resulting in pressure drop include pipe length, pipe bends and joints, and internal gas-against-gas and gas-against-pipe friction.

The example system 100 is configured to monitor pressure at a plurality of points, thereby providing control systems and techniques of operation that anticipate, detect and/or mitigate unsafe situations, and avoid unsafe situations resulting from network latencies, headend application latencies, and/or human delays. In the example system 100, the gas meter/gas pressure regulator 114 is configured to include edge detection and gas pressure notification systems and techniques 138. In an example, the techniques 138 are enabled by execution of software, which may be defined in memory and executed by a processor. Other devices shown in the system 100 may contain the same or similar edge detection and gas pressure notification systems and techniques 138. The edge detection and gas pressure notification systems and techniques 138 are configured and operate according to one or more of the examples shown, discussed and/or suggested by the examples of FIGS. 2-9 .

FIG. 2 shows an example gas delivery system 200 illustrating example functionality of groups of devices, particularly showing a data-gathering functionality. A first example group 202 of devices includes four gas meters 206-212. The first group 202 additionally includes two valves 214, 216. The valves may be associated with segment pipelines or “stub pipelines” off a main gas pipeline (e.g., pipes 104, 106 of FIG. 1 ). The valves 214, 216 may allow gas to be turned on/off to more than one gas service site (i.e., more than one gas metering device).

The first group 202 may also include a group data pool 218, which may be located in any desired location, such as a remote server, one or more of the gas metering devices, or a dedicated device, etc. The data pool 218 may include information regarding a topology of some or all of the gas delivery system 200, and time-stamped pressure measurements and/or pressure thresholds of gas pressure measuring devices in one or more groups of devices. The data pool 218 may also identify groups of devices according to geography and/or connectivity within the gas delivery system topology. A group may include devices on a segment of gas pipeline serving a related group of gas customers (e.g., related by use of a same gas main and/or related by physical distance between any two devices of less than a threshold value).

The example gas delivery system 200 may also include other group(s), represented for drawing simplicity by group 204 and gas meter 220. The number of groups and the number of devices in each group may be based on the needs, conditions, and design specification of a particular system, and are shown in FIG. 2 only to illustrate general concepts and not as requirements.

In an example, the gas consumption meters, valves, gas pressure-measuring devices, combined function devices, etc., may be configured in a group based on gas delivery system topology. In the example, some or all of the components (e.g., smart gas metering devices, valves, pipelines, etc.) along a gas pipeline serving a number of customer sites (associated with the smart gas metering devices) may be configured in a logical group. The pipeline may terminate after the last downstream customer's site. In some examples, an over-pressure event (e.g., gas pressure over a threshold) could be resolved by temporarily turning off the gas supply to the pipeline.

In an example of the operation of system 200, devices with pressure sensors (e.g., smart gas metering devices, etc.) can periodically compare their pressure readings to one or more high gas-pressure threshold values. The comparison may be made at prescribed intervals, random times, etc., as indicated by system design requirements, including available battery power, time since detection of an over-pressure event, and/or other considerations. If a device (e.g., a smart gas meter) detects that pressure has passed a relevant threshold value, the device can increase the rate of its gas-pressure sampling. Conversely, if the device detects normal gas pressure values for over a relevant threshold time value, it can decrease the rate of its gas-pressure sampling.

If a threshold gas-pressure value is exceeded, the device can send its latest pressure reading(s)—and in some examples, its relevant threshold values(s)—to its neighboring devices (e.g., devices within the group of devices) that also have gas pressure sensors.

Responsive to a message from a group member (e.g., smart gas metering device 208) sensing a higher than threshold gas pressure, other pressure sensing devices in the group (e.g., smart gas metering devices 206, 210, 212) can increase their rate of pressure sampling. Additionally, the other pressure sensing devices can add their own data set to the data pool 218 (e.g., a data pool associated with sensing devices in a geographic area and/or devices within a logical group). The data pool 218 may be used to determine if an over-pressure event is area-wide (e.g., caused by events on the distribution side) or if it is localized to the single service point and/or device. Such a collaboration between devices distributed on (or near) the edge of a gas distribution system reduces the chance that decisions will be made based on false positives.

Data from group 202 may be sent (e.g., by cellular or internet connection 222) to a headend device. In the example of FIG. 2 , the data sent to the headend device 224 may include an initial notification by one of the gas pressure-measuring devices that a high gas pressure event (e.g., gas pressure over a threshold) has been detected. The measured gas pressure and the threshold may be sent to the headend device. The threshold is relevant at least in that it puts into perspective what the preferred gas pressure is at the location at which the measurement was made. The headend device 224 may be a server of a utility company, a third-party contractor of the utility company, or may be another device. In an example, the data 226 received from gas pressure-measuring devices and/or groups of such devices may be displayed for the situational-awareness of human operator(s) and/or used in algorithms that are involved in data-gathering, data-processing, and response(s) to gas over-pressure events. Example responses may include damage prevention procedures, such as shutting valves to prevent increases in gas pressure.

FIG. 3 shows an example gas delivery system 300 containing enhancements to the gas delivery system 200 seen in FIG. 2 . In the example, the gas delivery system 300 performs data-processing functions that formulate response(s) to gas over-pressure events, and send appropriate commands to initiate the response(s). The responses may address local gas over-pressure events (e.g., detected by a single smart gas metering device) or area-wide gas over-pressure events (e.g., detected by plural smart gas metering devices within a group of devices).

In the example, an algorithm 302 (e.g., a “group algorithm”) may utilize data from the group data pool 218 of FIG. 2 to determine a response to an over-pressure event seen by: a gas pressure-measuring device from among those in a group; and/or a group of smart gas pressure-measuring devices. The algorithm 302 may be based at least in part on the techniques and methods presented in FIGS. 5 through 9 .

The group is typically based on a topology of the gas delivery system, and may include pipelines, smart gas meters (e.g., meters with gas pressure-measuring capabilities), other gas pressure gauges, valves, and other devices. The group algorithm 302 can consider the rate of pressure increase so that severity and urgency of the issue can be evaluated. If the rate of gas pressure increase is “slower” (e.g., a rate of change that is less than a threshold value), then the devices may provide instructions for an initial mitigating action that includes a service technician dispatched by the utility company. In contrast, if the group of devices (e.g., algorithm 302) determines that the situation is “faster” (e.g., a rate of change that is greater than the threshold value), then immediate mitigating action should be taken. The algorithm may direct the group of devices to perform automatic shutoffs of their own valves, send shutoff commands to valves in other devices around them, send alarms with pressure sampling data to the headend system for utility notification, and send alerting information to customers' cellular phones 304 and/or in-home devices 306 to warn the end-customer of the safety situation.

FIG. 4 shows an example gas delivery system 400 illustrating data collection, data transmission, and data utilization. A central office 402 may be operated by a utility company, a third-party contractor or other entity. The central office may be in communications with networks 404, such as the internet and/or cellular telephone networks, or proprietary networks. In some examples, a router device 406 may (optionally) be in communication with a plurality of devices in one or more groups 408, 410 of devices of the gas delivery system 400. In the example shown, the first group of devices includes smart gas metering devices 412-418 and the second group of devices 420-426. Each smart gas metering device may include hardware devices 428. In different examples, the hardware devices 428 may include one or more of a gas metering device, a gas pressure sensor, a radio, a processor, a memory device, and/or a gas valve, etc. The devices 428 may be configured (e.g., with software) to perform some or all of the edge detection and gas pressure recognition, notification, and mitigation/repair systems and techniques 138.

A database 430 may be located on the central office server 402 or may be distributed across a plurality of networked devices 412-426. The database 430 may be maintained with new data (e.g., gas pressure measurements, times, locations (device identification and/or service site), etc.) as the data becomes available. The database 430 may include topological relationships of networked devices. In examples, the topology may include information indicating which devices are attached to a particular gas main, a relationship describing connections between gas mains, gas supplies, etc. The database 430 may be used to track which devices are communicating with each other and/or able to communicate, the configuration of each device (e.g., gas meter, valve, pressure sensor), etc. The database 430 may include other relationships, such as RF signal strength between networked devices, battery strength of devices, radio type, modulation schemes configured for each device, etc.

Example Methods to Handle High Gas Pressures

In some examples of the techniques discussed herein, the methods of operation may be performed by one or more application specific integrated circuits (ASIC) or may be performed by a general-purpose processor utilizing software defined in computer readable media. In the examples and techniques discussed herein, the memory (e.g., the memory device(s) of hardware 428) may comprise computer-readable media and may take the form of volatile memory, such as random-access memory (RAM) and/or non-volatile memory, such as read only memory (ROM) or flash RAM. Computer-readable media devices include volatile and non-volatile, removable, and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data for execution by one or more processors of a computing device. Examples of computer-readable media include, but are not limited to, phase change memory (PRAM), static random-access memory (SRAM), dynamic random-access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to store information for access by a computing device.

As defined herein, computer-readable media does not include transitory media, such as modulated data signals and carrier waves, and/or signals.

If pressure in an area of a gas distribution system gets too high, it can cause pipe bursting, gas venting, enlarged and unsafe pilot lights, and possibly fires and explosions. Gas flows from higher pressures upstream to lower pressures downstream. Additionally, the gas pressure within a gas delivery system can vary from city gate regulators and meters in the system to the end service point regulators and meters. Example factors governing pressure drop include the length of runs (e.g., the length of gas mains), number of pipe bends and joints, and internal gas against pipe friction. By monitoring pressure at a plurality of points, the system increases the ability for utility companies to anticipate, detect and/or mitigate unsafe situations, and avoid unsafe situations with network latencies, headend application latencies, and human delays. The systems and techniques (e.g., smarter gas metering devices) at service points provide the means to self-monitor for unsafe situations. In some examples, the systems and techniques also monitor not only at the single point at which the equipment is installed, but also an area surrounding the location of the equipment. In the example, such monitoring is performed by exchanging information with smart metering devices at nearby service sites. In many examples, the gas delivery system performs actions that automatically mitigate unsafe situation(s).

Devices with pressure sensors (e.g., smart gas metering devices, etc.) can periodically compare their pressure readings to one or more high gas-pressure threshold values. If a device detects that pressure has passed one of the thresholds it can increase the rate of its pressure sampling and can send its latest pressure readings and thresholds to its neighboring devices that also have pressure sensors. The other pressure sensing devices can likewise increase their rate of pressure sampling and add their own data set to a group data pool (e.g., a data pool associated with sensing devices in a logical group defined according to a geographic area, according to pipelines, and/or according to a gas supply topology). The data pool may be used to determine if an over-pressure event is area-wide (e.g., caused by events on the distribution side) or if it is localized to the single service point and/or device. Such a collaboration between devices distributed on (or near) the edge of a gas distribution system reduces the chance that decisions will be made based on false positives.

The group algorithm can consider the rate of pressure increase so that severity and urgency of the issue can be evaluated. If the rate of gas pressure increase is “slow,” the devices may provide instructions for an initial mitigating action that includes a service technician dispatched by the utility company. In contrast, if the group of devices determines that the situation is real, urgent, and that immediate mitigating action needs to take place, the group of devices can perform automatic shutoffs of their own valves, send shutoff commands to valves in other devices around them, send alarms with pressure sampling data to the headend system for utility notification, and send information to in-home devices to warn the end-customer of the safety situation.

The logic that controls actions of the gas delivery system (e.g., that controls service site locations to shut off) relies on knowledge of the distribution system service point connections and location of regulators and/or gate valves that “segment” portions of that distribution system. Additionally, the physical distance between service points may be considered even if they are not on the same distribution line. Devices can know their group (or groups) via pre-programming (e.g., programming at time of manufacture), programming at install time, self-discovery, and/or by hearing network radio frequency (RF) messages. In other examples, devices can be configured to be within one or more groups via network or local communication based on distribution topology.

In some examples, the logic that controls actions of the gas delivery system can be based at least in part on a topology of the gas delivery system. The topology may include all the gas supply facilities, gas pipes, valves, gas meters and other devices used in gas supply. An augmented topology may include communications devices, such as radios that allows control circuits to operate the gas delivery devices (e.g., valves). The topology of the gas delivery system (with or without augmentation to include communications devices) may be instantiated in a database or other data structure.

In different examples, the techniques discussed herein could additionally and/or alternatively be applied to low-pressure situations in a gas distribution system. The low-pressure conditions are not as urgent as high-pressure conditions, but can help mitigate loss of pressure in a system which can lead to pilot lights going out and costly re-lighting processes.

FIG. 5 shows an example method 500 of detecting a high gas pressure condition. The method detects high gas pressure situation(s) within a gas delivery system. In an example, a first device (e.g., smart gas metering device) measures gas pressure and determines if that pressure is over a threshold value. If so, the first device sends a message to at least one other device. In an example, the message is sent to device(s) within a group of devices based on gas system topography (e.g., the group of devices are smart metering devices having a common gas supply line). The receiving devices may respond by indicating if they are experiencing a gas over-pressure condition. If so, the gas over-pressure condition is not localized at the first device. Alternatively, the second device(s) may indicate that it/they is/are not in an over-pressure condition, thereby suggesting that the over-pressure condition may be localized to the first device. An appropriate response may be made within the gas delivery system depending on if the over-pressure condition is localized to the first device, or more widely present within the group of devices. In examples, protective measures may be taken, such as closing valves providing gas to appropriate service sites.

At block 502, gas pressure is measured at a device to obtain a first gas pressure value. In the example of FIG. 1 , the first device may be the smart metering device 206, and may measure gas pressure at a customer's site.

At block 504, it is determined that the first gas pressure value exceeds a first threshold value. In the example, the smart metering device 206 may perform the calculation with respect to the first threshold value. In other examples, the calculation may be performed at a headend device or other location. In the example of block 506, in response to determining that the first gas pressure value exceeds the first threshold value, a rate at which gas pressure is measured is increased.

At block 508, at least one of the first gas pressure value, a threshold value, and an indication that the first gas pressure value exceeds the first threshold value is sent from the first device to second device(s). In some examples, the second device(s) to which data is sent are selected from among devices in a group also including the first device. By defining one or more groups of devices, the gas pressure information of one or more group members can be used synergistically to anticipate gas over-pressure events at other group members. In additional examples, the data is sent from the first device to devices selected based on a topology of the gas delivery system (e.g., the device(s) may be selected based on connection to a same gas main), possibly without formally defining groups of devices. In further examples, the data is sent from the first device to device(s) less than a threshold distance from the first device. In still further examples, the data is sent from the first device to device(s) based on one or more of the above examples.

At block 510, information comprising at least one of a second gas pressure value indicating gas pressure at the second device or an indication of whether the second gas pressure value exceeds a second threshold value is received. In a first example, the first device receives the information. In a second example, the information could be received at a headend server or other device at any location.

At block 512, “local” high gas-pressure event may be reported, if high gas pressure was detected only at the first device. In an example, a high gas-pressure event at the device may be based at least in part on the second gas pressure value being at or below the second threshold value. In the example, if the second gas pressure of the second device does not exceed that device's threshold value then only a local high gas-pressure event at the first device is reported.

At block 514, a “group-wide” high gas-pressure event may be reported, if high gas pressure was detected at the first device and at the second device(s). In an example, a high gas-pressure event within a distribution area of the device and the second device is reported (e.g., to a headend device and/or to all devices within the group) based at least in part on the second gas pressure value (at the second device) exceeding the second threshold value (which may or may not be the same as the first threshold value).

At block 516, a high gas-pressure event may be anticipated because the rate of gas pressure increase is high at any device, even if the gas pressure has not yet exceeded a threshold value. In an example, it may be determined that a rate of gas pressure increase (e.g., at the first device or second device) exceeds a third threshold value. When the rate of gas pressure increase is high (even if the actual gas pressure has not yet exceeded a threshold value) it may be important to realize that the gas pressure is changing fast (i.e., increasing), that an over-pressure event may happen soon, and that protective measures should be taken even before high gas pressure thresholds are exceeded.

At block 518, a first gas valve of the first device is closed based at least in part on the high gas-pressure event at the first device. In an example, the first gas valve may be closed in response to a local high gas-pressure event. In the example of block 520, gas valves at additional devices may be closed based on gas pressure exceeding respective thresholds of the additional devices. In an example, the second gas valve of the second device (e.g., the device discussed at block 510) may be closed in response to a high gas-pressure event at that device. In the example of block 522, devices within a group of devices are notified and/or directed to close their respective gas valves. In an example, this direction may be in response to high gas-pressure events at the first and second devices. Because the group of devices is based at least in part on the topology of the gas delivery system, all devices in the group may be under a high gas-pressure condition, and closing some or all of the gas valves within the group may be indicated.

FIG. 6 shows example techniques 600 for selecting a second device to which to send a message. At block 508 of FIG. 5 , information was sent from the first device (which recognized a gas over-pressure event at its location) to one or more other devices. In an example, the device sensing an over-pressure event attempts to determine if the over gas-pressure condition is limited in extent (e.g., limited to itself), or more broadly includes other devices. The techniques 600 include two examples, which may be used singly or in combination, to determine to which device(s) a first device that senses an over-pressure event should send over-pressure information and send a request (explicit or implied) for the receiving device to perform tasks, such as measuring gas pressure, increasing a frequency or rate of such measurements, comparing measurements to thresholds, and/or taking actions to lessen/prevent damage from a high gas pressure event. In some examples, if the first device sends its gas pressure information to one or more other devices, those device(s) may assume that the first device is experiencing an over-pressure event (i.e., the over-pressure event at the first device is why the message was sent). In other examples, if a threshold value is also sent by the first device, the second device(s) may readily determine the amount by which measured gas pressure at the first device exceeded a threshold of the first device.

At block 602, second device(s)—to which the first device may send gas pressure and/or threshold value information—may be selected from among a plurality of devices. In some examples, the selecting is based at least in part on data describing aspects of a topology of a gas delivery system to which the first device and the second device are connected, and wherein the selecting is performed prior to the sending. In some examples, the selecting is based at least in part on a distance between the first and second devices. If the distance between the first device and other devices is less than a threshold distance, the first device may send gas pressure and/or threshold value information to those devices.

At block 604, an RF signal strength of a signal sent by the second device is measured. The signal strength of the second device, measured at the first device, helps the first device determine a distance to the second device. The second device may be selected from among a plurality of devices based at least in part on the measured RF signal strength of each respective device from among the plurality of devices. In an example, a device is selected based on which device(s) appear to be closer to the first device, or which device(s) are less than a threshold distance from the first device.

FIG. 7 shows example techniques 700 for responding to a high gas pressure condition. The techniques 700 include two examples, which may be used singly or in combination, to mitigate or prevent damage to the gas supply system and/or customers' appliances and infrastructure that might otherwise result in an over-pressure event. In some examples, a valve is closed on a single device to prevent additional gas from entering a part of the gas delivery system, which would further increase the gas pressure. In other examples, valves are closed on multiple devices to prevent such damage.

At block 702, based at least in part on the second gas pressure value exceeding the second threshold value, a shutdown command is sent to a group of devices. In an example, each device in the group of devices is connected to a gas main to which the device is connected or is within a threshold distance of the device.

At block 704, based at least in part on the second gas pressure value exceeding the second threshold value, a supply of gas to a region within a gas distribution system is shut off. In an example, the region includes the device and the second device. In a further example, the region includes all devices (e.g., smart gas meters) attached to a same gas delivery pipe. In a further example, the region includes all devices within a group of devices, and the group is defined based at least on a database containing a topological description of the gas delivery system. The topological description of the gas delivery system may include a listing of devices in the system, their characteristics, and how, when, where, and/or to what they are connected.

FIG. 8 shows additional example techniques 800 for responding to a high gas pressure condition. The techniques 800 include three examples 802-806, which may be used singly or in one or more combinations, to send messages to devices (e.g., cellular devices, in-home devices, headend devices, etc.). The messages may be sent in response to a first device detecting over-pressure gas conditions or a second device that checked gas pressure conditions responsive to message(s) from the first device.

At block 802, a message may be sent to a first cellular phone or to a first in-home device associated with the first device (e.g., a smart gas meter). The message may warn the recipient of an over-pressure event, and may suggest a course of action (such as evacuation of the property). In a variation of block 802, the message may be sent to authorities (e.g., 911, emergency, the fire department, etc.). The message may include the nature of the over-pressure event, the address(es) of the event, a suggested course of action, etc.

At block 804, the message (or a similar message) may be sent to a second cellular telephone or to a second in-home device associated with a service site within a threshold distance of the first device. Messages (e.g., warnings) may be sent to additional service sites if the over-pressure event does not appear to be limited to a single service site.

At block 806, the message (or a similar message) may be sent to a headend device, based at least in part on at least one condition being true, the conditions including: the first gas pressure value exceeds the first threshold value; and the second gas pressure value exceeds the second threshold value.

FIG. 9 shows example techniques 900 for defining and using groups of devices, detection of a gas over-pressure condition, and reporting the over-pressure event affecting the group of devices. The techniques 900 include grouping devices based at least in part on gas system topography, determining that gas-pressure threshold(s) have been exceeded at one or more devices in a group of devices, and reporting gas over-pressure events in messages and/or warnings to users and/or authorities (e.g., 911). The reporting may be based at least in part on the group associated with the device(s) found to have over-pressure events. By recognizing common features of devices and grouping them, the reporting can include devices that are in danger of an over-pressure event but may not have even realized the situation. The failure to realize the situation may result from a frequency of gas pressure measurement. Accordingly, the use of groups leverages the measurements of one device (e.g., smart gas meter) to protect the service site of another device.

At block 902, a group of devices is defined based at least in part on a topology of a gas delivery system. In an example, the topology may be used to organize the group based on some or all devices related to, or attached to, a gas pipeline serving a number of customer sites. In a further example, each device of the group may be within a threshold distance of all other devices of the group. The devices may include a gas source (e.g., an LNG plant), a pipeline, a number of smart gas meters, gas valves, in-home devices, etc.

At block 904, it is determined that gas pressure measurements exceed respective thresholds at one or more devices within the group of devices. The number of devices with gas pressure that is over-pressure may be compared to a third threshold, such as to reduce false positives. In an example, one device measures gas pressure over a threshold and alerts other device(s) to measure their gas pressure and/or increase a frequency of gas pressure measurements.

At block 906, an over-pressure event that affects the group of devices is reported. The over-pressure event may be reported by one or more smart gas meters or other devices. The over-pressure event may be reported to the customer(s) at affected sites, including reports made to in-home devices, cellular telephones, etc. Reports may be sent to customer(s) at sites that are geographically near the affected sites. Alternatively, or additionally, reports may be sent to customer(s) at sites that are related to site(s) detecting the over-pressure event by aspects of the topology of the gas delivery system. For example, the aspects of the topology may include sites served by a same gas main, sites served by a same gas supply facility, sites having gas flow affected by same valve(s), etc.

Example Methods to Handle Low Gas Pressures

Techniques are described for detecting and responding to a low gas pressure condition within a gas delivery system (e.g., for natural gas delivery to homes and businesses). In one example, a first device measures gas pressure. As used herein, devices may be smart gas meters, gas valves, gas sensors (e.g., flowrate and pressure sensors), other devices, and/or combinations of such devices. In the example of FIG. 4 , a smart gas metering device 412 is configured for operation as a gas meter at a customer's site, and is configured to measure gas pressure.

If gas pressure that is less than a threshold value is detected (i.e., an under-pressure event), a message is sent to a nearby device. The nearby device either confirms that it also is experiencing an under-pressure condition or fails to confirm such a condition. If the under-pressure condition is confirmed by the nearby device, the condition may be related to other similarly situated devices. In an example, many or all devices on a gas main may experience a low gas pressure condition due to a leak in the gas main. If the under-pressure condition is not confirmed (i.e., shared) by the nearby device, the condition may be limited to the first device (e.g., a gas leak at or near a service site of the first device).

FIG. 10 shows example techniques 1000 for detecting and responding to a low gas pressure condition. In an example, the techniques 1000 may be performed at the smart gas meter level, as opposed to performance at the central office server. This may result in a faster and better result, by avoiding the risks of communications failure at a time of heightened system risks and increased communications. Also, while the techniques 1000 are described as being performed by a smart gas metering device (e.g., device 412 of FIG. 4 ), other smart gas metering devices are performing similar actions simultaneously with multiple devices within their range of communication. At block 1002, gas pressure at a first device is measured to obtain a first gas pressure value. Referring to the example of FIG. 4 , the smart gas metering device 412 measures gas pressure at the customer's site at which the device is located.

In the example of block 1004, a comparison is made, and it is determined that the first gas pressure value is less than a first threshold value. Responsive to the determination, at block 1006 a message is sent to a second device. In the example of FIG. 4 , the second device may be the smart gas metering device 416, and the message may be sent over a radio frequency (RF) link between the two devices. The message may include at least one of: (1) the first gas pressure value; (2) an indication that the first gas pressure value is less than the first threshold value; or (3) similar information.

At block 1008, information is received at the device. In the example of FIG. 4 , the information may be sent by device 416 and received by device 412. In an example, the information may include: (1) a second gas pressure value indicating gas pressure at the second device; and/or (2) an indication of whether the second gas pressure value is less than a second threshold value; or (3) similar information.

At block 1010, a report is sent. The report may be sent to a data collector, a server, or other device. In the example of FIG. 4 , the report may be sent to a server at the central office 402. The report may include the information of block 1012 or 1014. In the example of block 1012, the information indicates a low gas pressure event at the first device based at least in part on the second gas pressure value being at or above the second threshold value. That is, block 1012 is the circumstance wherein the second device does not have a low gas pressure condition. In the example of block 1014, the information indicates—e.g., based at least in part on the second gas pressure value being less than the second threshold value—that there is a low gas pressure event at the second device. Accordingly, there is a low gas pressure condition within a distribution area including at least the first device and the second device.

FIG. 11 shows example techniques 1100 for determining if a response to a low gas pressure condition should include increasing a data sample rate of a pressure sensor or closing a service valve controlling gas supply to the customer's service site. At block 1102, responsive to determining that the first gas pressure value is less than the first threshold value, a rate at which gas pressure is measured at the first device is increased. At block 1104, responsive to determining that the first gas pressure value has fallen below a third threshold value—wherein the third threshold is less than the first threshold value—a valve of the first device is closed. Thus, if the gas pressure is low, the rate of pressure measurements is increased. However, if the gas pressure goes even lower, then the service valve is closed.

FIG. 12 shows example techniques 1200 for maintaining data on gas service sites and using priority data to determine service sites that shut down (i.e., the gas service valve is closed) during a low gas pressure condition. At block 1202, a list of gas service sites is maintained. The list may include indications that some gas service sites (e.g., certain commercial or industrial customers) have lower priority than other service sites (e.g., hospitals). At block 1204, the first threshold value used by the first device and a third threshold value used by the first device is set (i.e., values for the threshold are set, fixed and/or determined). The threshold values may be set based at least in part on the list of gas service sites. The first device may be configured, and the threshold values may be set, so that if gas pressure at the first device is less than the third threshold value then a gas valve of the first device will close. In the example, the third threshold value is less than the first threshold value. Thus, gas pressure under the first threshold at the first device results in sending a report, while an even lower gas pressure (less than the third threshold) results in the gas service to the first device being shut off.

FIG. 13 shows example techniques 1300 for maintaining data on gas service sites and using priority data to set threshold values used to manage a low gas pressure condition. At block 1302, a list of gas service sites is maintained. In an example, the list could indicate that one customer is a hospital, and another customer is a carwash. In the example, the list may associate each type of service site with a service priority level. Different service priority levels may be associated with different threshold gas pressure values. In the example, the hospital may be associated with a high service priority level and a gas pressure threshold value that requires a lower gas pressure before service is turned off than, for example, the carwash. At block 1304, the first threshold value of the first device and the second threshold value of the second device are set and/or obtained based at least in part on the list of gas service sites and priority information for those sites.

FIG. 14 shows example techniques 1400 for using a rate of change of gas pressure to determine if a service valve at a service site should be closed. At block 1402, it is determined that a rate of gas pressure decrease exceeds a threshold value. In an example, rapidly decreasing gas pressure could be caused by a broken pipe or appliance. At block 1404, a gas valve (e.g., the service valve, controlling the entire gas flow to the service site) at the first device is closed. At block 1406, the first device reports to the second device that the rate of gas pressure decrease exceeded the third threshold value. In an example, the second device may be affected by the broken pipe affecting the first device. In a different example, the second device may not be affected by the broken appliance affecting the first device.

FIG. 15 shows example messaging 1500 sent to gas service customers and to a headend device. At block 1502, a first message is sent to a first cellular phone or to a first in-home device associated with the first device. Thus, the customer gets a message, either on a cellular phone or on a dedicated in-home device. At block 1504, a second message is sent to a second cellular telephone or to a second in-home device associated with the second device. In an example, the first device and the second device are attached to a same gas main. Also in the example, the low gas pressure event within the distribution area that includes the first and second devices is confirmed by the second device, i.e., based at least in part on the second gas pressure value being less than the second threshold value. At block 1506, a third message is sent to a headend device. In an example, the third message is sent at least in part on at least one condition being true, the conditions including the conditions of blocks 1508 and 1510. At block 1508, the first gas pressure value is less than the first threshold value, indicating a low gas pressure event localized to the first device. At block 1510, the second gas pressure value is less than the second threshold value, indicating that both devices are affected by the low gas pressure event.

FIG. 16 shows example use 1600 of grouped devices and related techniques to alleviate a low gas pressure condition. At block 1602, it is determined that gas pressure is decreasing for each device of a group of devices. The group of devices may include the first and second devices. At block 1604, one or more compressor stations or one or more city gate regulators are instructed to raise output gas pressure.

FIG. 17 shows example techniques 1700 for determining that a group of devices at a respective group of service sites should close their respective service valves in response to a low gas pressure condition. At block 1702, it is determined that gas pressure is decreasing for each device of a group of devices. In an example, the group of devices comprises the first and second devices. At block 1704, devices within the group of devices are instructed to (and/or receive instructions to) close their respective service valves. Thus, the grouping techniques 1700 provide a method to discontinue service to carwashes (and similar facilities) before discontinuing service to hospitals (and similar facilities).

FIG. 18 shows example techniques 1800 for maintaining a data structure, and using the data structure in a process by which gas supply and demand are regulated during a low gas pressure condition. At block 1802, a data structure is maintained. In an example, the data structure includes records of devices in a group of devices and respective gas pressure information of each device. In the example of FIG. 4 , the group 408 of devices includes at least the first device 412 and the second device 416 described with respect to earlier figures. At block 1804, instructions are sent to supply devices to increase gas to the group of devices based on information in the data structure. At block 1806, instructions are sent to (and/or received by) devices from among the group of devices to close their respective service valves. Accordingly, blocks 1804 and 1806 increase gas supply and reduce gas demand, respectively, in an effort to raise gas pressure.

FIG. 19 shows example techniques 1900 for using groups of devices to detect and report low gas pressure conditions. At block 1902, a group of devices is defined based at least in part on a topology of a gas delivery system. In an example, the devices in the group could be gas meters connected to the same gas main. In a different example, the devices in the group could be gas meters connected to similar facilities (e.g., hospitals). At block 1904, it is determined that gas pressure measurements are less than respective thresholds at a number of devices within the group of devices. In an example, the number of such devices exceeds a threshold or a threshold percentage of the group. At block 1906, responsive to the threshold being exceeded, an under-pressure event affecting the group of devices is reported. In the example of FIG. 4 , the report is sent to a server of the central office 402.

FIG. 20 shows example techniques 2000 for accessing and/or updating a database, such as to obtain or provide gas pressure data and/or a topological relationship of devices on the network. The database may be used in conjunction with other techniques described herein. At block 2002, a database is updated to include gas pressure measurements, measurement times, and measurement locations. In the example of block 2004, the updated data describes aspects of a topology of a gas delivery system to which the first device and the second device are connected.

FIG. 21 shows example techniques 2100 for accessing a database, obtaining information, and using the information to determine if a service valve should be closed. At block 2102, a database is accessed. In an example, the database describes aspects of a topology of a gas delivery system to which the first device and the second device are connected. In the example, the topology indicates how gas mains and gas metering devices are connected. At block 2104, a gas metering device is selected, based at least in part on information from the database. In an example, the metering device is one of a plurality of metering devices that are selected. The selection may be based in part on the plurality of metering device being attached to a same gas main, as indicated by the topology information. The selection may also be based in part on a known or suspected failure (e.g., a leak) of that gas main. At block 2106, service valves associated with one or more respective selected gas metering devices are closed.

FIG. 22 shows example techniques 2200 for grouping devices and managing the grouped devices. At block 2202, the first device and the second device are associated in a group. At block 2204, data generated by devices in the group is saved into a database. In an example, the data includes gas pressure measurements, times of measurements, and locations of measurements. At block 2206, service valves associated with one or more devices in the group are closed in response to the low gas pressure event. At block 2208, one or more gas pressure values are reported to a headend device (e.g., a server of the central office 402).

Example Systems and Devices

The following examples of a network edge detection and notification of gas pressure situation are expressed as numbered clauses. While the examples illustrate a number of possible configurations and techniques, they are not meant to be an exhaustive listing of the systems, methods, and/or techniques described herein.

1. A method, comprising: measuring gas pressure at a first device to obtain a first gas pressure value; determining that the first gas pressure value is less than a first threshold value; sending at least one of the first gas pressure value or an indication that the first gas pressure value is less than the first threshold value to a second device; receiving information comprising at least one of a second gas pressure value indicating gas pressure at the second device or an indication of whether the second gas pressure value is less than a second threshold value; and reporting one of: a low gas pressure event at the first device, based at least in part on the second gas pressure value being at or above the second threshold value; or a low gas pressure event within a distribution area comprising the first device and the second device, based at least in part on the second gas pressure value being less than the second threshold value.

2. The method of clause 1, additionally comprising: responsive to determining that the first gas pressure value is less than the first threshold value, increasing a rate at which gas pressure is measured at the first device; or responsive to determining that the first gas pressure value is less than a third threshold value, closing a valve of the first device, wherein the third threshold value is less than the first threshold value.

3. The method of clause 1, additionally comprising: maintaining a list of gas service sites having an indication that some gas service sites have lower priority than other service sites; and setting, based at least in part on the list of gas service sites, the first threshold value used by the first device and a third threshold value used by the first device, wherein gas pressure at the first device less than the third threshold value results in a gas valve closure at the first device, and wherein the third threshold value is less than the first threshold value.

4. The method of clause 1, additionally comprising: maintaining a list of gas service sites, wherein each service site is associated with at least one threshold gas pressure value; and setting the first threshold value of the first device and the second threshold value of the second device based at least in part on the list of gas service sites.

5. The method of clause 1, additionally comprising: determining that a rate of gas pressure decrease exceeds a third threshold value; closing a gas valve at the first device; and reporting to the second device that the rate of gas pressure decrease exceeded the third threshold value.

6. The method of clause 1, additionally comprising: shutting off, based at least in part on the second gas pressure value being less than the second threshold value, a supply of gas to a region within a gas distribution system, wherein the region includes the first device and the second device.

7. The method of clause 1, additionally comprising: sending a first message to a first cellular phone or to a first in-home device associated with the first device; sending a second message to a second cellular telephone or to a second in-home device associated with the second device, wherein the first device and the second device are attached to a same gas main, and wherein the low gas pressure event within the distribution area comprising the first device and the second device is confirmed based at least in part on the second gas pressure value being less than the second threshold value; and sending a third message to a headend device, based at least in part on at least one condition being true, the conditions comprising: the first gas pressure value being less than the first threshold value; and the second gas pressure value being less than the second threshold value.

8. The method of clause 1, additionally comprising: determining that gas pressure is decreasing for each device of a group of devices, wherein the group of devices comprises the first device and the second device; and instructing one or more compressor stations or one or more city gate regulators to raise output gas pressure.

9. The method of clause 1, additionally comprising: determining that a group of devices indicate that gas pressure is decreasing, wherein the group of devices comprises the first device and the second device; and instructing devices within the group of devices to close their respective valves.

10. The method of clause 1, additionally comprising: maintaining a data structure that comprises records of gas pressure information of respective devices in a group of devices, wherein the group of devices comprises at least the first device and the second device; sending instructions to supply devices to increase gas to the group of devices based on information in the data structure; and sending instructions to devices from among the group of devices to close their respective valves.

11. The method of clause 1, additionally comprising: defining a group of devices based at least in part on a topology of a gas delivery system; determining that gas pressure measurements are less than respective thresholds at a number of devices within the group of devices, wherein the number of devices exceeds a third threshold; and responsive to the third threshold being exceeded, reporting an under-pressure event affecting the group of devices.

12. A device, comprising: a gas pressure sensor; a radio; a processor; memory, having defined thereon statements, which when executed by the processor perform actions comprising: measuring gas pressure, by operation of the gas pressure sensor, to obtain a first gas pressure value; determining that the first gas pressure value is less than a first threshold value; sending to a second device, by operation of the radio, at least one of the first gas pressure value or a first indication of whether the first gas pressure value is less than the first threshold value; receiving, by operation of the radio, information comprising at least one of a second gas pressure value, indicating gas pressure at the second device, or a second indication of whether the second gas pressure value is less than a second threshold value; reporting a low gas pressure event within a distribution area comprising the device and the second device based at least in part on the second gas pressure value being less than the second threshold value; and reporting a low gas pressure event at the device based at least in part on the second gas pressure value being at or above the second threshold value.

13. The device as recited in clause 12, additionally comprising: a database comprising topological relationships of devices within a gas supply system to which the device is connected, wherein the second device, to which data is sent, is selected based at least in part on reference to the database indicating that the device and the second device are on a same gas main.

14. The device as recited in clause 12, wherein the actions additionally comprise: measuring signal strength of an incoming message, thereby obtaining a signal strength value; and selecting devices to which to send information using the signal strength value.

15. The device as recited in clause 12, wherein: the device additionally comprises a gas valve; and the actions additionally comprise closing the gas valve based at least in part on the first gas pressure value.

16. The device as recited in clause 12, wherein the actions additionally comprise: sending gas shutoff commands to devices based at least in part on two or more low gas pressure events; sending messages with pressure sampling data to a headend system; sending a first message to at least one of a first cellular telephone and an in-home device to warn a customer of the low gas pressure event at the device; sending a second message to a second cellular telephone or to a second in-home device associated with the second device, wherein the device and the second device are attached to a same gas main, and wherein the low gas pressure event within the distribution area comprising the device and the second device is confirmed based at least in part on the second gas pressure value being less than the second threshold value; and shutting a gas valve responsive to the low gas pressure event at the device.

17. One or more computer-readable media storing computer-executable instructions that, when executed by one or more processors, configure a computing device to perform acts comprising: measuring gas pressure by operation of a first device to obtain a first gas pressure value; determining that the first gas pressure value is less than a first threshold value; sending, to a second device, at least one of the first gas pressure value or an indication that the first gas pressure value is less than or equal to the first threshold value; measuring gas pressure by operation of the second device to obtain a second gas pressure value; determining that the second gas pressure value is less than a second threshold value; and reporting a low gas pressure event within a distribution area comprising the first device and the second device based at least in part on the second gas pressure value being at or below the second threshold value; or reporting only a low gas pressure event at the first device, based at least in part on the second gas pressure value being at or above the second threshold value.

18. One or more computer-readable media as recited in clause 17, additionally comprising: updating a database to include gas pressure measurements and gas pressure measurement locations, wherein the database includes data describing aspects of a topology of a gas delivery system to which the first device and the second device are connected.

19. One or more computer-readable media as recited in clause 17, additionally comprising: accessing a database describing aspects of a topology of a gas delivery system to which the first device and the second device are connected, wherein the topology comprises data indicating how gas mains and gas metering devices are connected; selecting a gas metering device based at least in part on information from the database; and closing a service valve associated with the selected gas metering device.

20. One or more computer-readable media as recited in clause 17, additionally comprising: associating the first device and the second device in a group; saving the first gas pressure value and the second gas pressure value in a database, wherein the data comprises gas pressure measurements, times of measurements, and locations of measurements; closing valves associated with one or more devices in the group in response to the low gas pressure event indicated by data in the database; and reporting the first gas pressure value and the second gas pressure value to a headend device.

CONCLUSION

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claims. 

1. A method, comprising: measuring gas pressure at a first device to obtain a first gas pressure value; determining that the first gas pressure value is less than a first threshold value; sending at least one of the first gas pressure value or an indication that the first gas pressure value is less than the first threshold value to a second device; receiving information comprising at least one of a second gas pressure value indicating gas pressure at the second device or an indication of whether the second gas pressure value is less than a second threshold value; and reporting one of: a low gas pressure event at the first device, based at least in part on the second gas pressure value being at or above the second threshold value; or a low gas pressure event within a distribution area comprising the first device and the second device, based at least in part on the second gas pressure value being less than the second threshold value.
 2. The method of claim 1, additionally comprising: responsive to determining that the first gas pressure value is less than the first threshold value, increasing a rate at which gas pressure is measured at the first device; or responsive to determining that the first gas pressure value is less than a third threshold value, closing a valve of the first device, wherein the third threshold value is less than the first threshold value.
 3. The method of claim 1, additionally comprising: maintaining a list of gas service sites having an indication that some gas service sites have lower priority than other service sites; and setting, based at least in part on the list of gas service sites, the first threshold value used by the first device and a third threshold value used by the first device, wherein gas pressure at the first device less than the third threshold value results in a gas valve closure at the first device, and wherein the third threshold value is less than the first threshold value.
 4. The method of claim 1, additionally comprising: maintaining a list of gas service sites, wherein each service site is associated with at least one threshold gas pressure value; and setting the first threshold value of the first device and the second threshold value of the second device based at least in part on the list of gas service sites.
 5. The method of claim 1, additionally comprising: determining that a rate of gas pressure decrease exceeds a third threshold value; closing a gas valve at the first device; and reporting to the second device that the rate of gas pressure decrease exceeded the third threshold value.
 6. The method of claim 1, additionally comprising: shutting off, based at least in part on the second gas pressure value being less than the second threshold value, a supply of gas to a region within a gas distribution system, wherein the region includes the first device and the second device.
 7. The method of claim 1, additionally comprising: sending a first message to a first cellular phone or to a first in-home device associated with the first device; sending a second message to a second cellular telephone or to a second in-home device associated with the second device, wherein the first device and the second device are attached to a same gas main, and wherein the low gas pressure event within the distribution area comprising the first device and the second device is confirmed based at least in part on the second gas pressure value being less than the second threshold value; and sending a third message to a headend device, based at least in part on at least one condition being true, the conditions comprising: the first gas pressure value being less than the first threshold value; and the second gas pressure value being less than the second threshold value.
 8. The method of claim 1, additionally comprising: determining that gas pressure is decreasing for each device of a group of devices, wherein the group of devices comprises the first device and the second device; and instructing one or more compressor stations or one or more city gate regulators to raise output gas pressure.
 9. The method of claim 1, additionally comprising: determining that a group of devices indicate that gas pressure is decreasing, wherein the group of devices comprises the first device and the second device; and instructing devices within the group of devices to close their respective valves.
 10. The method of claim 1, additionally comprising: maintaining a data structure that comprises records of gas pressure information of respective devices in a group of devices, wherein the group of devices comprises at least the first device and the second device; sending instructions to supply devices to increase gas to the group of devices based on information in the data structure; and sending instructions to devices from among the group of devices to close their respective valves.
 11. The method of claim 1, additionally comprising: defining a group of devices based at least in part on a topology of a gas delivery system; determining that gas pressure measurements are less than respective thresholds at a number of devices within the group of devices, wherein the number of devices exceeds a third threshold; and responsive to the third threshold being exceeded, reporting an under-pressure event affecting the group of devices.
 12. A device, comprising: a gas pressure sensor; a radio; a processor; memory, having defined thereon statements, which when executed by the processor perform actions comprising: measuring gas pressure, by operation of the gas pressure sensor, to obtain a first gas pressure value; determining that the first gas pressure value is less than a first threshold value; sending to a second device, by operation of the radio, at least one of the first gas pressure value or a first indication of whether the first gas pressure value is less than the first threshold value; receiving, by operation of the radio, information comprising at least one of a second gas pressure value, indicating gas pressure at the second device, or a second indication of whether the second gas pressure value is less than a second threshold value; reporting a low gas pressure event within a distribution area comprising the device and the second device based at least in part on the second gas pressure value being less than the second threshold value; and reporting a low gas pressure event at the device based at least in part on the second gas pressure value being at or above the second threshold value.
 13. The device as recited in claim 12, additionally comprising: a database comprising topological relationships of devices within a gas supply system to which the device is connected, wherein the second device, to which data is sent, is selected based at least in part on reference to the database indicating that the device and the second device are on a same gas main.
 14. The device as recited in claim 12, wherein the actions additionally comprise: measuring signal strength of an incoming message, thereby obtaining a signal strength value; and selecting devices to which to send information using the signal strength value.
 15. The device as recited in claim 12, wherein: the device additionally comprises a gas valve; and the actions additionally comprise closing the gas valve based at least in part on the first gas pressure value.
 16. The device as recited in claim 12, wherein the actions additionally comprise: sending gas shutoff commands to devices based at least in part on two or more low gas pressure events; sending messages with pressure sampling data to a headend system; sending a first message to at least one of a first cellular telephone and an in-home device to warn a customer of the low gas pressure event at the device; sending a second message to a second cellular telephone or to a second in-home device associated with the second device, wherein the device and the second device are attached to a same gas main, and wherein the low gas pressure event within the distribution area comprising the device and the second device is confirmed based at least in part on the second gas pressure value being less than the second threshold value; and shutting a gas valve responsive to the low gas pressure event at the device.
 17. One or more computer-readable media storing computer-executable instructions that, when executed by one or more processors, configure a computing device to perform acts comprising: measuring gas pressure by operation of a first device to obtain a first gas pressure value; determining that the first gas pressure value is less than a first threshold value; sending, to a second device, at least one of the first gas pressure value or an indication that the first gas pressure value is less than or equal to the first threshold value; measuring gas pressure by operation of the second device to obtain a second gas pressure value; determining that the second gas pressure value is less than a second threshold value; and reporting a low gas pressure event within a distribution area comprising the first device and the second device based at least in part on the second gas pressure value being at or below the second threshold value; or reporting only a low gas pressure event at the first device, based at least in part on the second gas pressure value being at or above the second threshold value.
 18. One or more computer-readable media as recited in claim 17, additionally comprising: updating a database to include gas pressure measurements and gas pressure measurement locations, wherein the database includes data describing aspects of a topology of a gas delivery system to which the first device and the second device are connected.
 19. One or more computer-readable media as recited in claim 17, additionally comprising: accessing a database describing aspects of a topology of a gas delivery system to which the first device and the second device are connected, wherein the topology comprises data indicating how gas mains and gas metering devices are connected; selecting a gas metering device based at least in part on information from the database; and closing a service valve associated with the selected gas metering device.
 20. One or more computer-readable media as recited in claim 17, additionally comprising: associating the first device and the second device in a group; saving the first gas pressure value and the second gas pressure value in a database, wherein the data comprises gas pressure measurements, times of measurements, and locations of measurements; closing valves associated with one or more devices in the group in response to the low gas pressure event indicated by data in the database; and reporting the first gas pressure value and the second gas pressure value to a headend device. 